This is a continuation proposal to use new detailed dynamic measures of change over time in neighborhoods to dramatically advance our understanding of the impact of social context on behavior in several new directions. Our plan is to take advantage of a unique social setting in Nepal to investigate the social and economic factors which alter family formation processes and cause fertility decline. The aim of this research is to find empirical answers to five specific questions regarding the beginning of a transition from high fertility and no use of birth control to low fertility and the widespread use of birth control. These questions are: 1) To what extent do changes in the social and economic context influence family formation processes, particularly marriage, the timing of the first birth and contraception to terminate childbearing? 2) How do qualitative dimensions of these contextual changes, such as the quality of new schools or health services, shape family formation processes? 3) Do changes in the family organization of individual life courses transmit these contextual effects? 4) Does the family organization of neighbors life courses transmit these contextual effects? and 5) Do variations in attitudes and beliefs, or neighbors attitudes and beliefs, explain these consequences of community-level changes? Although our preliminary research demonstrates significant effects of community-level social and economic change on the adoption of birth control, we still know little about the extent to which these same changes influence other dimensions of family formation or the mechanisms through which these influences are transmitted. The large number of unanswered theoretical questions regarding the causes of fertility decline, along with the high priority policy makers place on reducing fertility in South Asia, make this research particularly timely.